Software defined network (SDN) is a networking paradigm that decouples network control and forwarding functions. The decoupling of the control plane from the data plane allows for centralization of network control, enabling effective policy administration and flexible management. The centralization of network control facilitates various network functionalities, such as network measurements, traffic engineering, enhanced quality of services, and enhanced access control. With the growing availability of SDN-enabled nodes and protocols, many organizations have started deploying SDN networks.
A virtual private network (VPN) extends a private network across a public network, and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. Users may request a VPN using a VPN-specific service model.